In the field of emergency medicine, establishing an airway is often the first step in saving a life. The default procedure for creating an airway is endotracheal intubation by which a tube is inserted through the mouth and into the trachea. When endotracheal intubation is unsuccessful or impossible due to severe head or neck trauma, then an airway can be established surgically by inserting a tube directly into the trachea through the front of the neck. This procedure is commonly known as a tracheotomy. Emergency tracheotomies are a last resort effort to create an airway, and therefore their success is usually critical to patient survival.
Although commonly known as a tracheotomy, there are in fact two different surgical airway procedures: tracheostomies and cricothyroidotomies. The latter is presently the standard practice in emergency medicine. A percutaneous procedure by means of the Seldinger Technique is generally regarded as the safest method for performing a cricothyroidotomy. It involves inserting an airway tube through the cricothyroid membrane, which lies just below the thyroid cartilage (the Adam's apple in men). In this technique, the cricothyroid membrane is palpated between the thyroid and cricoid cartilages. An incision is made in the cricothyroid membrane. An over-the-needle catheter is placed over a hollow needle and the needle and catheter are together inserted into the trachea through the incision with an attached syringe remaining outside of the trachea. The needle is then aspirated by applying back pressure on the syringe to confirm that it is within the trachea. The needle and syringe are then removed with the catheter remaining within the trachea. A guide wire is then fed through the catheter into the airway and the catheter is then removed. A dilator is then fed over the guide wire to dilate the opening to permit spontaneous inhalation and exhalation.
Although only used in last resort efforts to form an airway, emergency cricothyroidotomies have a dangerously high rate of complications including excess time to complete the procedure, incision error including inability to identify the cricothyroid membrane, inappropriateness for children under a certain age, burn or infection at the incision site, tube misplacement, hemorrhaging, and cartilage injury. Often, the unprotected sharp end of a needle utilized during a cricothyroidotomy is inserted too far into the trachea puncturing the soft posterior wall causing injury and severe complications. Also, there is a risk that the needle will not be inserted to the correct depth, because of variations in thickness of neck tissue overlying the trachea. If the needle is not inserted far enough, its tip may be located in the anterior tissues surrounding the trachea instead of in the trachea itself. Similar problems and injuries can arise upon introduction of the guide wire. Cricothyroidotomies often result in long term complications, and are often performed incorrectly, causing damage to the larynx, thyroid gland, esophagus, and trachea. Additionally, the airway from the cricothyroidotomy is temporary, lasting only about thirty to forty-five minutes, due to the inability for carbon dioxide to leave the bloodstream efficiently. Thus, when patients enter the hospital with a cricothyroidotomy, doctors must remove it, repair the cricothyroid membrane, and perform a proper tracheostomy. This creates extra work for the hospital and presents additional risk to the patient.
Relatively speaking, the tracheostomy is a lower risk procedure which has a reduced risk of tracheal perforation. Moreover, since the tracheostomy is performed at a location on the neck that is lower than the location for performing a cricothyroidotomy, there are circumstances where injuries would preclude performing a cricothyroidotomy, where performing a tracheostomy may still be appropriate.
Unlike a cricothyroidotomy, a tracheostomy is a definitive airway which is placed directly into the trachea about two centimeters above the sternal notch. Tracheostomies are the desired method of surgical intubation for in-hospital procedures. Despite being a safe and successful in-hospital procedure, no known current techniques or products allow tracheostomies to be performed in the pre-hospital emergency field. For example, the current tracheostomy procedure is not well adapted for conducting in the field because it requires the use of a real-time bronchoscopic visualization during the procedure to ensure that the needle is not being inserted through the posterior tracheal wall and possibly into the esophagus.
In the pre-hospital emergency field, the cricothyroidotomy is the preferred method because access to the trachea is obtained through the cricothyroid membrane, which is a single small piece of tissue. By contrast, in a tracheostomy, access to the trachea is more difficult requiring breaking through the skin and a layer of cartilage. The tracheostomy is more complex than the cricothyroidotomy requiring a higher level of skill, and requiring the stable environment of an operating room.
The ability to perform emergency tracheostomies in the field prior to the patient's arrival at the hospital will address the risks of current cricothyroidotomies by dramatically reducing steps and complexity, increasing patient safety, increasing ease of use, and decreasing risk of infection. Having the option to perform emergency tracheostomies in the field should increase confidence in emergency responders who previously may not have felt comfortable with the current cricothyroidotomy procedure. Finally, performing emergency tracheostomies in the field will eliminate the need for redundant surgical intubation in the hospital and will likely decrease the high complication rate of emergency cricothyroidotomies.